Telephone multiplex equipment with pulse amplitude modulation - superimposes audible signals onto speech without using modulator

摘要

The receiver (APE) receives signal pulses from the bus bar (SS) at its input (SE). The capacitor (C), controlled by clock pulses (tan), stored the signal pulses thus providing at the output (SA) a replica of the original speech signal. A gate (G) allows a second pulse (Psig) also to control the capacitor charge/discharge cycle. This appears to the subscriber as a click whose tone and pitch can be varied. Thus audible signals directed to a specific subscriber can be superimposed on speech, in TDM systems employing pulse amplitude modulation. The need for modulators for this purpose can be avoided.